Search

Your search keyword '"Grobet, P.J."' showing total 40 results
Start Over Author "Grobet, P.J."
40 results on '"Grobet, P.J."'

1. Reversible tetrahedral-octahedral framework aluminum transformation in zeolite Y

Author

Wouters, B.H., Chen, T.-H., and Grobet, P.J.

Subjects
Zeolites -- Research, Aluminum -- Research, Lattice dynamics -- Research, Chemistry
Abstract

Hydration of a mildly calcined zeolite Y sample was observed to cause the local eradication of the zeolite lattice. Therefore, besides the dealumination of the framework, a partial hydrolysis of framework Al-O bonds transpires which produces a framework connected Al-OH species. These framework Al-OH sites can host water molecules to produce octahedrally coordinated Al species.

Published
1998

34. The relative stability of zeolite frameworks

Author

Ooms, G., Santen, van, R.A., Jackson, R.A., Catlow, C.R.A., Grobet, P.J., Mortier, W.J., and Inorganic Materials & Catalysis

Subjects
Lattice energy, Chemistry, Mineralogy, Thermodynamics, Faujasite, engineering.material, Hückel method, Mordenite, Ion, Condensed Matter::Materials Science, Adsorption, Lattice (order), engineering, Zeolite
Abstract

This paper addresses the question whether there is a theoretical basis to an apparent relation that has been experimentally observed between the lattice topology and the Al/Si ratio of zeolites. Calculations are presented for three lattices formed with different Al/Si ratios: faujasite, mordenite and ZSM-5. The relative stabilities of these lattices are studied as a function of Al/Si ratio in the presence or absence of adsorbed water. Na + ions are taken as the compensating ions. Two contrasting techniques, lattice energy minimisation and extended Huckel theory, are used in this study. It is found that the energy differences of Al-free lattices are very small (- 10 kJ) and tend to decrease with density. The stability of the zeolite lattice appears to be a sensitive function of Al content. Wide pore zeolites tend to become stabilized with respect to medium pore zeolites at high Al content.

Published
1988

35. Clusters of Terminal Groups in ZSM-5: A Study Performed by Silylation and 29Si CP MAS NMR

Author

Kraushaar, B., Ven, van de, L.J.M., Haan, de, J.W., Hooff, van, J.H.C., Grobet, P.J., Mortier, W.J., Vansant, E.F., Schulz-Ekloff, G., Materials and Interface Chemistry, Inorganic Materials & Catalysis, and Chemical Engineering and Chemistry

Subjects
Crystallography, Silylation, Chemistry, Inorganic chemistry, ZSM-5, Zeolite
Abstract

Silylation with trimethylchlorosilane and subsequent analyses of the products by 29 Si CP MAS NMR is an appropriate method for the characterization of terminal groups in ZSM-5. It can be shown that the terminal groups are clustered and belong to gaps of missing T-atoms (Si or Al). These gaps are part of regularly 4-membered and larger rings in the lattice of ZSM-5. During prolonged heat treatment of ZSM-5 the amount of internal terminal groups decreases. We propose a T-jump mechanism of the gaps resulting in a migration of the terminal groups towards the external surface of the zeolite particles.

Published
1988

Catalog

Books, media, physical & digital resources
See catalog results